Article:
Signs Of The
Last Times
Research results of the new study indicate the rapid reversals of Earth's magnetic field which occurred about 550 million years ago is responsible for destroying a huge portion of the ozone layer. This destruction has, in turn, allowed a higher concentration of ultraviolet radiation into our atmosphere, which proved fatal to the life forms of the Ediacaran Period. As a result, an evolutionary flight after the widespread extinction had triggered the Cambrian explosion of more complex animal groups.
The so-called Ediacaran Period, from about 635 to 541 million years ago, ended in a massive extinction, named the Kotlinian Crisis. Large, unusual soft-bodied creatures, up to 1 m (3.3 feet) in size, resided on or inside the shallow horizontal burrows, underneath a thick mass of bacteria which coated the seafloor, and acted as a barrier between the top water layer and the sedimented area at the bottom. After the extinction, the Cambrian explosion followed, and, new, more complex, species evolved. The bacteria, which prevented the oxygen from reaching under the seafloor during the Ediacaran were broken down, and the seabed had become inhabitable.
